This spectacular meteorological phenomenon is known as an Asperitas cloud formation. Asperitas clouds sometimes form in areas with stable, cool, sinking air near the outskirts of thunderstorms, and are particularly common in the Plains states of the United States. Despite their ominous appearance, the clouds are not a harbinger of severe weather, often occurring during the morning or midday hours following convective thunderstorm activity.

This video was taken with an iPhone 6 by Dr. Alan Walters from the University Hospital window in Augusta, GA. Walters, an anesthesiologist at the hospital, said he taped his phone to the window while he put an epidural In a patient. “I guess I was finally in the right place at the right time,” Walters said.

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